wic: Add argument --hidden to default imager

Add argument --hidden to avoid MS Windows prompting to format
partition after flashing to a USB stick, SD card on another media.
Set Bit 0 (RequiredPartition) to mark that the partition is
required for the platform to function on GUID Partition Table
(GPT).

The new argument simplifies setting RequiredPartition on GPT
through a WKS file and the default imager plugin. Otherwise,
without this feature, to achieve the same result a new imager
plugin has to be implemented and set in WIC_CREATE_EXTRA_ARGS.

(From OE-Core rev: 7a111ff58d7390b79e2e63c8059f6c25f40f8977)

Signed-off-by: Leon Anavi <leon.anavi@konsulko.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/ksparser.py

@@ -171,6 +171,7 @@ class KickStart():
         part.add_argument('--rootfs-dir')
         part.add_argument('--type', default='primary',
                 choices = ('primary', 'logical'))
+        part.add_argument('--hidden', action='store_true')
 
         # --size and --fixed-size cannot be specified together; options
         # ----extra-space and --overhead-factor should also raise a parser

scripts/lib/wic/partition.py

@@ -59,6 +59,7 @@ class Partition():
         self.updated_fstab_path = None
         self.has_fstab = False
         self.update_fstab_in_rootfs = False
+        self.hidden = args.hidden
 
         self.lineno = lineno
         self.source_file = ""

scripts/lib/wic/plugins/imager/direct.py

@@ -605,6 +605,13 @@ class PartitionedImage():
                                 (self.path, part.num, part.system_id),
                                 self.native_sysroot)
 
+            if part.hidden and self.ptable_format == "gpt":
+                logger.debug("Set hidden attribute for partition '%s' on disk '%s'",
+                             part.num, self.path)
+                exec_native_cmd("sfdisk --part-attrs %s %s RequiredPartition" % \
+                                (self.path, part.num),
+                                self.native_sysroot)
+
     def cleanup(self):
         pass